fbsql_pconnect() acts very much like
fbsql_connect() with two major differences:

First, when connecting, the function would first try to find a
(persistent) link that's already open with the same host,
username and password. If one is found, an identifier for it
will be returned instead of opening a new connection.

Second, the connection to the SQL server will not be closed when
the execution of the script ends. Instead, the link will remain
open for future use.

This type of links is therefore called 'persistent'.

Parameters

hostname

The server host name.

username

The user name for the connection.

password

The password for the connection.

Return Values

Returns a positive FrontBase persistent link identifier on success, or
FALSE on error.